1. Field of the Invention
This invention relates to a process by which improved operation of a continuous coal deashing process can be effected, and more particularly but not by way of limitation, to a process for maintaining the fluidity of fluid-like phases formed during the deashing process.
2. Description of the Prior Art
Various coal deashing processes have been developed in the past wherein coal has been treated with one or more solvents and processed to separate the resulting insoluble coal products from the soluble coal products.
U.S. Pat. Nos. 3,607,716 and 3,607,717, assigned to the same assignee as the present invention describe processes wherein coal liquefaction products are contacted with a solvent and the resulting mixture is separated into a heavy phase containing the insoluble coal products and a light phase containing the soluble coal products. In such processes, the light phase is withdrawn and passed to downstream fractionating vessels wherein the soluble coal products are separated into multiple fractions.
The separation is effected in these processes by maintaining rigorous control of the process conditions. The failure to maintain the required conditions often will cause the process to become inoperable.
In the event the process conditions are not maintained, the heavy phase, which exhibits fluid-like properties under the operating conditions of the process, solidifies into a solid mass. The solidified mass, once formed, will not regain the fluid-like properties upon return of the process conditions of their former limits. Further, the solid has a tendency to spall away from the surfaces of the apparatus on which it has formed and to plug additional downstream apparatus. Thus, operation of the coal deashing process must be discontinued to permit maintenance personnel access to the apparatus to remove the solidified material. To effect the solids removal, it is necessary to disassemble and mechanically clean the interior of the apparatus and conduits leading to downstream apparatus.
It would be desirable to provide a process by which, in the event the operating conditions of the coal deashing process were not maintained, the formation of the solidified mass can be avoided and continuous operation can be maintained without the necessity of dissassembling the apparatus and conduits.